RadioButtonControllers redefine the response to a button-click.
While toggles (i.e. ToggleControllers) change state with every click,
radioButtons will only do so for an off-to-on transition.
They will NEVER turn themselfes off with a click.
To turn a radioButton off, another button in its buttonGroup must
be turned on and thereby (via the buttonGroup) turn the first button off.
You can place both toggles (for 'zero-or-one-on' behavior) or
radiobuttons (for 'one-on' behavior) into a buttongroup.